#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main() {
//	system("start https://www.lanqiao.cn/problems/17037/learning/");

	char ch;
	int ans = 0;
	while (cin >> ch) {
		if ((ch - '0') % 2)
			ans++;
	}
	cout << ans;

	return 0;
}
